The PCA9544A, PCA9544APW is a 1-of-4 bidirectional translating multiplexer, controlled via the I2C-bus. The SCL/SDA upstream pair fans out to fourSCx/SDx downstream pairs, or channels.
The pass gates of the multiplexer are constructed such that the VDDpin can be used to limit the maximum high voltage which is passedby the PCA9544A. This allows the use of different bus voltages on each SCx/SDx pair, so that 1.8 V, 2.5 V or 3.3 V parts can communicate with 5 V parts without any additional protection. External pull-up resistors pull the bus up to the desired voltage level for each channel. All I/O pins are 5 V tolerant.
Block Diagram :
1. 1-of-4 bidirectional translating multiplexer
2. I2C-bus interface logic; compatible with SMBus
3. 4 active LOW interrupt inputs
4. Active LOW interrupt output
5. 3 address pins allowing up to 8 devices on the I2C-bus
6. Channel selection via I2C-bus
7. Power-up with all multiplexer channels deselected